Project Summary/Abstract: A group of NIH supported investigators requests funding to purchase a stopped-flow spectrometer. The instrument will be used to gain comprehensive knowledge of protein complexes, including interactions with appropriate ligands, by studying their kinetics and key dynamics to characterize function and elucidate possible roles in disease modulation. Specifically, the stopped-flow spectrometer will be used to: understand the binding behavior of aggregation inhibitors related to neurodegenerative diseases, probe binding kinetics and dynamics of protein-ligand complexes in solution, study the binding dynamics and conformational changes of shell proteins from bacterial microcompartments, elucidate the folding pathway of membrane proteins, evaluate hemoglobin binding and hemin transfer and measure reaction kinetics of novel bioorthogonal chemistry for the rapid labeling of biomolecules towards molecular imaging applications. The information obtained from this technology enables accurate monitoring, and analysis of reactions that occur on a sub-second level. On campus, only one stopped-flow spectrometer exists. It was purchased nearly 20 years ago and has outdated capacity. Therefore, access to this valuable technology is currently lacking at UCLA. The specific instrument we are requesting is a SX-20 (standard with an absorbance PMT and 150W Xe lamp), produced by Applied Photo Physics. The SX-20 represents the state-of-the-art in stopped-flow technology and exhibits exceptionally high fluorescence sensitivity, optimum speed and robustness for steady state and kinetic experiments. Thus, it is well suited to support the UCLA research community?s needs. The stopped-flow spectrometer will be located in the UCLA-DOE Biochemistry Instrumentation Facility where it will be accessible to the entire UCLA research community. A highly experienced Ph.D.-level staff member and a research technician, with full salary support from UCLA, will be responsible for operating, maintaining, and training individuals on the instrument. UCLA will provide additional funds to support the service contract for the stopped-flow spectrometer to ensure that it is properly serviced for long-term utilization by the broad user community at UCLA.